This invention relates to improved head assemblies for reading/writing data on a storage medium. This invention also relates to actuators and disk drives that employ the improved head assemblies.
Disk drives of the type that receive data storage media typically have a head assembly for communicating with the storage medium. The data storage cartridge may be of the type that is removable from the disk drive. The storage medium may be disc shaped, and if so, the data storage cartridge may be referred to as a disk cartridge. The head assembly may include a pair of sliders. Each slider is typically mounted on an actuator that is mounted within a disk drive. Additionally, each of the sliders may have a read/write head for interfacing with a storage medium of a disk cartridge. The sliders are also commonly referred to as read/write heads.
Generally, the actuator on which the head assembly is mounted moves between a retracted position and an interfacing position. In the retracted position, the heads are disposed in a position that minimizes the likelihood of damage to the heads from either dynamic or static forces. When a disk cartridge has not been inserted into the disk drive, the actuator holds the heads in this retracted position. When a disk cartridge is inserted into the disk drive, the actuator moves the heads to the interfacing position. In the interfacing position, the actuator is in a position in which the heads can interface with the storage medium that has been inserted into the disk drive.
The storage medium with which the head assembly may interface may have a top surface and a bottom surface. Preferably, in the interacting position the storage medium is disposed between the sliders of the head assembly. One of the sliders may be disposed proximal to the top surface, and one of the sliders may be disposed proximal to the bottom surface. In operation, the storage medium of the disk cartridge is rotated between the sliders and an air bearing is created between the storage medium and the sliders. As the storage medium is rotated, the storage medium "rides" on this air bearing and the heads interface with the storage medium.
The design of head assemblies is significant because it effects the ability of the heads to interface with the storage medium of the disk drive. In particular, the ability of the heads to interface with the storage medium is a function of the spacing between the sliders and the storage medium. The spacing between the sliders and the media is important because it effects the ability of the disk drive to communicate with the media. Ordinarily, the sliders fly very low with respect to the media. As the distance between the media and the sliders increases, the signal degrades. With the development of higher density media, it is desired to develop sliders that have even lower fly heights then those previously developed.
For instance, one of the concerns when designing head assemblies is that the spacing between the read/write heads and the storage medium be relatively constant. If the spacing between the read/write heads and the storage medium is not relatively constant, this can cause a degradation in the ability of the heads to interface with the storage medium. The importance of maintaining the spacing between the storage medium and the heads relatively constant is even more pronounced in disk cartridges that have storage mediums with a relatively high density.
In order to maintain an appropriate spacing between the read/write heads and the storage medium, the air bearing created between the slider and the storage medium must be relatively constant. At high speeds, the flexible storage medium tends to flutter and therefore the importance of maintaining the spacing between the read/write heads and the storage medium is even more pronounced at high speeds. In addition to being dependent on the speed of rotation of the storage medium, the air bearing is a function of the geometry of the head assemblies and the storage medium. Therefore, the geometry of these components is of particular importance.
In addition to effecting the performance of the head assembly, the spacing between the head assembly and the storage medium also effects the life of both the read/write heads and the storage medium. For instance, if the storage medium fluctuates, the storage medium and the heads may wear unevenly and their respective lives may be reduced. Furthermore, if the air bearing pressure is relatively high, the storage medium and the heads will wear at a faster rate. The amount of fluctuation of the storage medium is a function of the geometry of the head assembly and the storage medium. Manufacturing imperfections in the design of head assemblies and variations in head assemblies due to large design tolerances have the potential to cause an imbalance of forces between the head assembly and the storage medium and subsequent fluctuations of the storage medium. Therefore, it is important to design head assemblies, so that the manufacturing tolerances are relatively low and the likelihood of manufacturing imperfections are reduced.
Previous designs of magnetic head assemblies are exemplified in U.S. Pat. Nos. 5,636,085 (Jones et al.), entitled "Magnetic Read/Write Head Assembly Configuration With Bleed Slots Passing Through Rails To Stabilize Flexible Medium While Attaining Low Fly Heights With Respect Thereto," and 4,974,106 (White et al.), entitled "Non-Contact Magnetic Head Assembly For A Flexible Medium Disk Drive." Jones et al., which is also owned by the assignee of the invention described in this application, and White et al. both describe magnetic head assemblies. The inventions described in these patents are directed to improved magnetic head assemblies, but may be used with other types of head assemblies such as optical head assemblies.
Recently, higher density storage media has been and is being developed. Previously, the iomega Zip.RTM. disk cartridge was considered to have a relatively high density. Even higher density magnetic media are being developed. The sliders and head assembly disclosed in the Jones et al. patent was designed to interface with the magnetic media, such as the Zip.RTM. disk cartridge. Although the sliders taught by Jones et al. have been sufficient for use with disk cartridges that have the density about equal to that of the Zip.RTM. disk cartridges, the advent of higher density magnetic media requires sliders that can better communicate with higher density media.
The slides, described in Jones et al., have a relatively low fly height. However, this fly height has proven to be insufficient for operation with higher density media. The head assembly of this invention improves upon that of Jones et al. to improve the ability of the disk drive to communicate with higher density media.
This invention includes improved head assemblies for disk drives. This invention also includes disk drives and disk drive actuators that employ the improved or head assemblies of this invention.